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GROUNDWATER. Groundwater. The Hydrologic Cycle. Groundwater. Groundwater. porosity. Vadose zone. Phreatic zone. Groundwater. Phreatic zone. Groundwater. Porosity vs. Permeability: Porosity – the amount of water a rock can hold
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Groundwater The Hydrologic Cycle
Groundwater porosity Vadose zone Phreatic zone
Groundwater Phreatic zone
Groundwater • Porosity vs. Permeability: • Porosity– the amount of water a rock can hold • Permeability– the amount of water that can move through a rock in a given amount of time Which is more important?
Groundwater What is an aquifer? a layer of rock from which water can be easily extracted A layer of rock through which water does not move readily is called an aquitard or aquiclude
Groundwater An unconfined aquifer
Groundwater A confined (artesian) system
Groundwater How fast does groundwater move? Between: 1 meter/day, and 1 meter/year On average, ~ 10 cm/day What are the consequences of this slow movement?
Groundwater Artificial recharge ponds, N. California
Groundwater How does groundwater erode? Groundwater can only erode by dissolution, usually helped by carbonic acid. Limestones are particularly susceptible Solution channels in limestone, England
Groundwater An area dominated by groundwater erosion is called karst topography
Groundwater Evolution of cave system
Groundwater Satellite image of a karst terrain
Groundwater Areceibo, Puerto Rico – SETI radio antenna
Groundwater Sinkholes
Groundwater Winter Park, FL
Groundwater Sinkhole swallows 2 cars, St. Louis, November 26, 2007
Groundwater Karst towers, China
Groundwater The Stone Forest, China
Groundwater Infilled sinkholes
Groundwater Red paleosols (Molas Fm) in Leadville Ls, Molas Lake
Groundwater How does groundwater transport its sediment? Only one way, in solution. This is what makes hard water, but dissolved load typically only in parts per million (ppm)
Groundwater How does groundwater deposit its sediment? By precipitation. This may occur within pore spaces, helping lithify sediments, or in open spaces as dripstone
Groundwater Gypsum stalactites, Lechuguilla, NM
Groundwater Calcite cement in sandstone
Groundwater SiO2 carried by groundwater replaces trees
Groundwater • Types of groundwater: • meteoric • connate • magmatic Any of the above may also behydrothermalwater
Groundwater Issues with groundwater use: • Pros: • agricultural, industrial, & • domestic water • geothermal energy • natural filtration • Cons: • ground subsidence • depletion • pollution • salt water encroachment
Groundwater Groundwater use by state
Groundwater Geothermal test well, Nevada
Groundwater Subsidence due to groundwater extraction, Mexico City
Groundwater Subsidence due to groundwater extraction, San Joaquin Valley, CA
Groundwater Salt water encroachment